. >> reporter: but as defense secretary panetta told norah o'donnell of "cbs this morning" earlier this month, the u.s. has a different red line. >> when they make the decision to go ahead and build a nuclear weapon, that, for us, is a red line. >> reporter: u.s. intelligence does not believe iran has made that decision yet. but netanyahu said it is too dangerous to rely on intelligence to detect the decision made in secret. so he set his red line on something he can see-- uranium merichment. panetta used to worry israel ringt strike iran as early as this spring or summer. judging by what netanyahu said today, the time to worry will be next spring. >> pelley: david, thank you. the state department said today it's withdrawing more staff from mbe u.s. embassy in tripoli, libya, temporarily, they said, for security reasons. dee department wouldn't say whether there had been a threat. earlier this month, the u.s. consulate in benghazi, libya, was attacked and burned, and ambassador chris stevens and three other americans were killed. that attack took place amid violent protests that broke o